Heart valve and apparatus for replacement thereof

ABSTRACT

Apparatus and methods for replacing a heart valve within a vessel. The apparatus includes a replacement heart valve and a plurality of commisure stabilizers connected to the commisures of the heart valve in a removable manner. The commisure stabilizers position and stabilize the commisures in the proper positions as the replacement heart valve is secured within the vessel. The commisure stabilizers may be removed following securement of the replacement heart valve within the vessel. An expansion or retraction device of the invention assists in properly positioning the valve within the vessel.

[0001] This application is a divisional of application Ser. No.09/310,891 filed May 12, 1999 (now pending), the disclosure of which isfully incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention generally relates to heart valvereplacement and, more particularly, to replacement heart valves andapparatus used during their implantation.

BACKGROUND OF THE INVENTION

[0003] A popular option for aortic valve replacement is to retain thenative aortic root and the normal coronary artery attachments and securethe replacement prosthesis inside the patient's own aorta. With thisprocedure, only the valve is replaced and not the entire root. It isunnecessary to re-attach the coronary arteries and, should repeatsurgery be necessary, a surgeon must only replace the valve and not anentire section of the aorta. When a surgeon replaces the aortic valve inthis manner, the patient is first placed on a heart-lung machine and thesection of the aorta having the aortic valve is clamped off to allowaccess. That section of the aorta is therefore collapsed andunpressurized leaving a pressurized section connected to the heart-lungmachine. The unpressurized section of aorta is then opened and thediseased valve is removed in its entirety, including careful removal ofcalcium deposits within the aorta and annulus. The aorta and sinotubularjunction are then sized and the surgeon prepares the appropriatereplacement valve. The surgeon then sutures the inflow or annular end ofthe replacement valve into the inside of the aorta. When these suturesare drawn tight, the valve is pulled inside the aorta when approximately20 sutures are then applied around the annular end. The commisures ofthe replacement valve, which extend from the annular end, may or may notneed to be affixed to the aorta as discussed below.

[0004] Two major types of prosthetic or replacement heart valves exist.The first general type of valve is a mechanical prosthesis whichincludes commisures that are self-supporting and do not need to beaffixed to the aortic wall. Mechanical prostheses are generally formedentirely of artificial material, such as carbon fiber, titanium, dacronand teflon. While these mechanical prostheses are durable, relativelyquick to implant and generally easy to manipulate during surgery, theyalso have certain disadvantages. For example, due to the artificialmaterials used in their construction, blood clots can form on the valveand subsequently cause valve failure. If the clot dislodges from thevalve, the clot can lodge in a downstream vessel and cause stroke ororgan ischemia. For these reasons, patients with mechanical heart valvesmust take anticoagulants for the rest of their lives. Anticoagulantsbring about their own complications in some patients, including internalbleeding or other side effects.

[0005] The second major type of prosthetic or replacement heart valve isa biologic valve. This category includes valves harvested from humancadavers, i.e., allografts or homografts, or animal tissue generallyharvested from cows and pigs. More recently, there has been increasingeffort to develop synthetic biologically compatible materials tosubstitute for these natural tissues. Among their advantages, biologicprostheses generally do not require lifelong anticoagulation as they donot often lead to clot formation. These valves are provided in stentedor unstented forms. A stented valve includes a permanent, rigid framefor supporting the valve, including the commisures, during and afterimplantation. The frames can take the form of a wire or other metalframework or a plastic frame encased within a flexible fabric covering.Unstented valves do not have built-in commisure support so surgeons mustuse their skill and best judgement to determine the optimal site ofimplantation inside the patient's native aorta to maintain valvecompetence. When securing the valve commisures, obstruction of thepatient's native coronary arteries must be avoided or myocardialinfarction may result.

[0006] There are many limitations to procedures utilizing permanentlystented biologic replacement valves. First, allografts (human cadaverdonor valves) are not generally available with permanent frames orstents. Second, the frames or stents can take up valuable space insidethe aorta such that there is a narrowing at the site of valveimplantation. This narrowing leads to pressure gradients and increasedloads on the left ventricle and, therefore, increased incidence ofhypertrophy and reduced patient survival. The frame includes artificialmaterials which can increase the risk of new infection or perpetuate anexisting infection. It is also very important to realize that althoughthe permanent frames or stents guarantee alignment of the commisures,they cause very high stresses on the commisures when the valve cuspsmove between open and closed positions. A patient's natural commisuresare not placed under significant strain during opening and closing ofthe valve due to the natural resilience of the aorta. On the other hand,artificially mounted valves place the commisures under strain duringoperation of the valve due to the rigid materials of the frame. Overtime, the valve cusps tend to decay under this strain and manifestcalcification and tears which can lead to valve failure.

[0007] In many situations, biologic replacement heart valves arepreferred in the unstented form due to the drawbacks mentioned above.Such valves are more resistant to infection when implanted free of anyforeign material attachments, such as stents or frames. Also, the heartvalve is more efficient when used without a stent. Efficiency refers tothe pressure gradient across the valve during use. Natural human valveshave almost no pressure gradient. When a natural heart valve is replacedby a biologic heart valve with a low pressure gradient, complicationssuch as hypertrophy arise less often and result in improved patientsurvival.

[0008] Despite the known advantages of using biologic prosthetic heartvalves without artificial supporting devices such as permanent stents orframes, relatively few surgeons employ this surgical technique due toits high level of difficulty. When unsupported or unstented byartificial devices, such as permanent stents, biologic replacement heartvalves have a flimsy, soft and flexible nature. That is, the commisuresof the heart valve do not support themselves in the proper orientationfor implantation. For these reasons, it is very difficult to secure thecommisures properly into place. In this regard, the surgeon mustgenerally suture the individual commisures of the heart valve in exactlythe proper orientation to allow the valve to fully and properlyfunction.

[0009] During valve replacement surgery, an L-shaped retractor is placedinside the aorta to pull it open for access purposes. While thisprovides exposure, it distorts the aorta and may give the surgeon anincorrect impression of the correct valve position. Next, and especiallywith regard to unstented biologic valve procedures, the surgeon mustguarantee that the commisures pass straight up the aorta at roughlyright angles to the plane of the annulus. There is very littletechnology to help the surgeon correctly place the stentless replacementvalve. To help confirm that the leaflets are correctly spaced at 120°apart, surgeons may use a disc having markings 120° apart. The surgeoncan use this to roughly estimate the spacing by placing it near thedistal ends of the commisures. However, this provides only a roughguide. For example, it is possible to equally space the commisures atthe upper end and still have a valve placed in a skewed position.Finally, the aorta is not a straight tube at the surgical site, butinstead flares outward at the surgical site. The valve must conform tothe flare of the aorta at this location. Once the surgeon has completedan inspection for these three elements, i.e., correct spacing atapproximately 120° between the commisures, correct perpendicularposition of the commisures relative to the annulus plane, andappropriate conformation to the flare of the aorta, the surgeon mustsuture the commisures to the wall of the aorta. As this is done, it isnecessary to make sure there is no encroachment on the ostia or originsof the coronary arteries. After the valve commisures are attached to theaorta and proper orientation and positioning is confirmed, the surgeoncloses the aorta.

[0010] Following surgery, there is a risk that the aorta will dilate atthe sinotubular junction months or years later and draw the valvecommisures and attached cusps apart from each other. This will causeinsufficiency and failure due to leakage through the valve. There is afurther need for methods to ensure that late enlargement of thesinotubular junction does not necessitate reoperation for late valveinsufficiency and failure.

[0011] In general, there is an increasing need for devices which improvethe efficiency and reliability of implanting replacement heart valves.In conjunction with this, there is a need to improve these procedures sothat all surgeons, not just those with the highest skill levels, canimplant heart valves with superior results.

SUMMARY OF THE INVENTION

[0012] The present invention generally provides apparatus directed atsolving problems, such as those described above, with regard toreplacing a heart valve within a vessel. In one general aspect, theinvention provides a replacement heart valve and a plurality oftemporary commisure stabilizers. More particularly, the replacementheart valve will generally have an annular base and a plurality ofspaced apart commisures extending from the annular base at spaced apartpositions. The valve may be formed of animal tissue, such as valvesharvested from pigs, cows or human donors. Optionally, the valve may beformed from synthetic, biologically compatible material. With thetypical aortic valve replacement, there will be three commisures spacedroughly 120° apart. Each commisure includes a proximal end connectedwith the annular base and an opposite distal end. The plurality ofcommisure stabilizers are connected to the commisures in a removablemanner. These commisure stabilizers position and stabilize thecommisures of the replacement heart valve as a surgeon secures thereplacement heart valve in place within the vessel. The commisurestabilizers, in the instance of an aortic valve replacement, positivelyorient the commisures at the 120° spaced apart positions and generallyperpendicular to a plane which contains the annular base of the heartvalve.

[0013] Following securement of the replacement heart valve within thevessel, the commisure stabilizers are preferably removed to avert thevarious disadvantages of permanent stents or frames. However, there maybe situations in which a particular surgeon desires to leave one or moreof the commisure stabilizers in place and the invention advantageouslyprovides for this option as well. In the preferred embodiment, thecommisure stabilizers are connected together at spaced apart distalpositions, for example, by a generally annular member. Each commisurestabilizer preferably comprises at least one elongate member attachablein a manner allowing removal from the distal end of the respectivecommisure following implantation of the heart valve.

[0014] The replacement heart valve can include respective receivingelements for the commisure stabilizers. These may comprise pockets,loops or other structure adapted to receive the stabilizers in a mannerallowing removal by a surgeon at the distal end of the commisures afterimplantation. The commisure stabilizers may also be removably affixed toother supporting structure, such as the generally annular memberdescribed above. This, for example, will allow the surgeon to remove theannular member or other supporting structure for easier suturing access,while at least temporarily leaving the commisure stabilizers in placefor positioning purposes. After suturing and/or other securement of thevalve, the commisure stabilizers would be removable to achieve the fulladvantages of this invention.

[0015] Each commisure stabilizer may further comprise at least twospaced apart elongate members or, more preferably, three elongatemembers. One or more of these members may curve or flare outwardly in alengthwise direction to urge the commisures of the replacement heartvalve against the flared interior wall of the vessel. The outer elongatemembers may also angle or curve away from the central elongate member toextend along opposite edge portions of the respective commisures.

[0016] In another aspect of the invention, the positioning andstabilizing device may be formed in a collapsible manner allowinginsertion into the vessel in a collapsed state and subsequent expansionfor positioning and stabilizing the valve commisures during securementof the valve within the vessel. For example, the positioning andstabilizing device may be at least partially formed of a shape memorymaterial allowing the positioning device to be collapsed and expanded asnecessary. This aspect of the invention may also be practiced in othermanners, such as through the use of hinged or otherwise collapsible andexpandible structures.

[0017] In accordance with another aspect of the invention, a flexiblematerial may connect the distal ends of the three commisures. This willprevent the commisures from moving radially apart due to latesinotubular enlargement. This material may also be secured to theinternal wall of the vessel to help prevent the need for reoperation dueto the complications of late enlargement of the sinotubular junction asdescribed above.

[0018] A method of implanting a replacement heart valve in accordancewith the invention includes inserting the replacement heart valve into apatient, connecting at least one commisure stabilizer to each of thecommisures of the replacement heart valve either before or afterinserting the replacement heart valve, securing the replacement heartvalve within the patient using the commisure stabilizers to orient thecommisures of the replacement heart valve, and removing one or more ofthe commisure stabilizers from the patient leaving the securedreplacement heart valve in place. Other methods of utilizing apparatusas described herein are also within the scope of this invention as willbe apparent.

[0019] These and other objects, advantages, and features of theinvention will become more readily apparent to those of ordinary skillin the art upon review of the following detailed description of thepreferred embodiments, taken in conjunction with the accompanyingdrawings and as more generally set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a partially fragmented perspective view of an aortaundergoing a valve replacement operation with an unstented biologicreplacement valve in the process of insertion;

[0021]FIG. 2 is a view similar to FIG. 1, but showing the initialremovable attachment of a positioning and stabilizing device havingcommisure stabilizers constructed in accordance with one embodiment ofthe invention;

[0022]FIG. 3 is a perspective view similar to FIG. 2, but showing thepositioning and stabilizing device fully inserted and the properlypositioned and stabilized commisures being sutured in place;

[0023]FIG. 4 is a perspective view similar to FIG. 3, but showing thefully implanted heart valve;

[0024]FIG. 4A is a cross sectional view taken along line 4A-4A of FIG.4;

[0025]FIG. 5 is a perspective view showing an alternative embodiment ofa positioning and stabilizing device being removed from a replacementheart valve following implantation;

[0026]FIG. 6 is a perspective view of another alternative positioningand stabilizing device constructed in accordance with the invention;

[0027]FIG. 6A is a cross sectional view taken along line 6A-6A of FIG.6;

[0028]FIG. 7 is a perspective view of another alternative embodiment ofa positioning and stabilizing device;

[0029]FIGS. 8A and 8B are perspective views of another alternativepositioning and stabilizing device respectively shown in collapsed andexpanded conditions;

[0030]FIG. 9 is a perspective view of an alternative replacement heartvalve and removable positioning and stabilizing device constructed inaccordance with the invention;

[0031]FIG. 9A is a perspective view of the apparatus shown in FIG. 9with the positioning and stabilizing device removed;

[0032]FIG. 9B is a fragmented and enlarged view of the positioning andstabilizing device of FIGS. 9 and 9A showing the separable partsthereof;

[0033]FIG. 10 is a perspective view of another alternative replacementheart valve and removable positioning and stabilizing device constructedin accordance with the invention;

[0034]FIG. 11 is a perspective view of an aortic expansion deviceconstructed in accordance with the invention;

[0035]FIG. 12 is a perspective view of an alternative aortic expansiondevice;

[0036]FIG. 13A is a top view of the expansion device illustrated in FIG.12, but shown in a collapsed condition; and

[0037]FIG. 13B is a top view of the expansion device shown in FIG. 12 inan expanded condition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038]FIG. 1 illustrates an aorta 10 which a surgeon has incised tocreate an opening 12 after a patient has been placed on a heart-lungmachine. One or more retractors 14 may be used by assistants to gainaccess to opening 12. Aorta 10 may be partially incised as shown or itmay be fully incised across its transverse dimension. During thisprocedure, the patient's heart 16, disposed below the surgical site, isnormally in an arrested state due to the use of the heart-lung bypassmachine and cardioplegia.

[0039] An unstented replacement valve 20 is further shown within aorta10 in an initial flimsy, unsupported condition. In this case, a fabriccovering 22 is stitched on the outside of the biologic tissue 24, whichmay be human or other animal tissue or synthetic material. Replacementvalve comprises typically three commisures 26, 28, 30 extending from anannular base 32. Replacement valve 20 has been inserted within aorta 10such that annular base 32 is disposed at the annulus 34 of aorta 10.Conventional sutures 36 may be used as shown to pull replacement valvewithin aorta 10 until it resides on annulus 34 in a known manner.

[0040] As further shown in FIG. 4A, a plurality of sutures 54 aretypically placed around the annular base 32 and into annulus 34.Replacement valve 20 must be disposed within aorta 10 so as not toocclude orifices 38, 40 communicating with the left and right coronaryarteries (FIG. 2). As additionally shown in FIG. 4A, the typical aorticreplacement valve includes three cusps 42, 44, 46, respectivelyconnected with the three commisures 26, 28, 30 for movement between openand closed positions as the heart beats to pump blood into the aorta.Sealing lines of contact 48, 50, 52 are formed between the respectivecusps 42, 44, 46. To maintain an effective seal along lines 48, 50, 52,commisures 26, 28, 30 must be positioned and secured within aorta 10 ina precise manner. In this regard, each commisure should preferablyextend in a relatively perpendicular, non-skewed manner along theinterior aortic wall 10 a, and in a manner that is essentiallyperpendicular to annular base 32. If this is not done, strain will beplaced on commisures 26, 28, 30 and an effective seal between cusps 42,44, 46 may eventually be lost. Undue strain on commisures 26, 28, 30 cancause decay and calcification and eventually lead to valve failure andeither death or a second surgical operation.

[0041]FIGS. 2 and 3 illustrate one embodiment of a positioning andstabilizing device 60 constructed in accordance with the invention.Generally, positioning and stabilizing device 60 may be used in atemporary manner while securing commisures 26, 28, 30 to aortic wall 10a. Positioning and stabilizing device 60, in this embodiment, includesan annular portion 62 connected with a plurality of stabilizers 64, 66,68, each taking the form of a single elongate member. Each stabilizer64, 66, 68 preferably bows outwardly along its length so as to generallyconform to a flared region 70 of the aortic root. As one of manypossible temporary securement methods, each stabilizer 64, 66, 68 isslipped between fabric covering 22 and biologic tissue 24 of replacementvalve 20. In the case of a valve which does not have a fabric covering,other securing structure such as suture loops, hooks, etc., may be usedto attach stabilizers 64, 66, 68. This temporary connection may be madebefore replacement valve 20 is inserted into aorta 10 or after valve 20is inserted within aorta 10. In the preferred embodiments, assembly of apositioning and stabilizing device and replacement valve, such as device60 and valve 20, is felt to be best accomplished prior to surgery toallow for insertion as a unit. As shown in FIG. 3, once replacementvalve 20 and positioning and stabilizing device 60 have been securedwithin aorta 10, with stitches 54 already placed at annulus 34, suturingof commisures 26, 28, 30 can begin. This may be accomplished using atypical needle 72 and suturing thread 74 manipulated by a grippingimplement 76. The surgeon places sutures 78 in this manner along theentire periphery of each commisure 26, 28, 30. It will be appreciatedthat other manners of securing replacement valve 20 to aorta 10 may beused in accordance with the invention and, for example, include gluing,stapling or other mechanical fasteners. FIG. 4 illustrates thecompletely secured replacement valve 20 implanted within aorta 10. Itwill be appreciated that, in this embodiment, once positioning andstabilizing device 60 has been removed from the pockets formed betweenfabric covering 22 and biologic tissue 24, the distal ends 26 a, 28 a 30a may be stitched to the aortic wall 10 a.

[0042]FIG. 5 illustrates one alternative embodiment of a replacementvalve 20′ useful in accordance with the invention. Replacement valve 20includes pockets 80 on the outside of each commisure 26, 28, 30 forreceipt of an alternative positioning and stabilizing device 90. Likethe first embodiment, positioning and stabilizing device 90 can includean annular portion 92 and a plurality of three stabilizers 94, 96, 98.In this embodiment, each stabilizer further comprises multiple elongatemembers adapted to be removably inserted within pockets 80. Morespecifically, each stabilizer 94, 96, 98 comprises respective elongatemembers 94 a-c, 96 a-c and 98 a-c. As will be appreciated fromstabilizer 96, outer elongate members 96 a, 96 c curve outwardly fromthe middle elongate member 96 b. In this manner, outer members 96 a, 96c extend within respective pockets 80 along the outer curved edges 28 b,28 c of commisure 28. The remaining stabilizers 94, 98 function in asimilar manner. It will be further appreciated that each stabilizer 94,96, 98 bows outwardly, as in the first embodiment, to conform to theflare 70 at the aortic root. Stabilizers 94, 96, 98 are flexible enoughto be withdrawn, as shown in FIG. 5, from pockets 80 after suturing ofeach commisure 26, 28, 30 as previously described. Positioning andstabilizing device 90 may be formed from various materials and invarious configurations for this purpose. These may include metals, superelastic alloys, or plastics.

[0043]FIGS. 6 and 6A illustrate another alternative positioning andstabilizing device 100 constructed in accordance with the invention. Inthis embodiment, an annular portion 102 is removable from a plurality ofcommisure stabilizers 104, 106, 108. In this manner, positioning andstabilizing device 100 may be used as described above with respect todevices 60 and 90, except that annular portion 102 may be removed foreasier suturing access or other securement access when securingcommisures 26, 28, 30 (FIG. 4) to aortic wall 10 a. One of manypossibilities for facilitating this function is shown in FIG. 6 and FIG.6A in the form of connectors 110, 112, 114. Each of these connectors mayreceive a stabilizer 104, 106, 108 in a removable fashion with a slightinterference fit. As best shown in FIG. 6A, an end portion 104 a ofstabilizer 104 may be received with a slight interference fit against aresilient tab 116. The other stabilizers 106, 108 may have a similarstructure, as exemplified by end 108 a shown in FIG. 6. Many otherfastening structures are possible other than this schematicallyillustrated example.

[0044]FIG. 7 illustrates another alternative positioning and stabilizingdevice 120 having a generally similar construction and function todevice 90 shown in FIG. 5. Device 120 may be formed from a single lengthof wire, for example, and includes portions 122, 124, 126 analogous tothe previously described annular portions. A connector 128 may beprovided to connect opposite ends of the wire. Stabilizers 130, 132, 134are formed with three sections each for purposes previously described inconnection with FIG. 5. These sections 130 a-c, 132 a-c, 134 a-c servesimilar functions to position and stabilize the commisures of areplacement heart valve, and device 120 may be removed from the heartvalve in previously described manners.

[0045]FIGS. 8A and 8B illustrate another alternative positioning andstabilizing device 140 constructed from a shape memory material such asNitenol. As shown in FIG. 8A, device 140 may be collapsed in each adetached form with respect to a heart valve, as shown, or whileconnected to a replacement heart valve for insertion within thepatient's aorta as a unit. Upon the application of heat or electriccurrent once inserted within the aorta, device 140 expands to theposition shown in FIG. 8B and may then be used as previously describedto position and stabilize the heart valve commisures duringimplantation. As shown in FIGS. 8A and 8B, one illustrative example ofthis device also includes an annular portion 142 and respectivethree-legged commisure stabilizers 144, 146, 148.

[0046]FIGS. 9 and 9A illustrate another heart valve replacementapparatus 160 constructed in accordance with the invention. In thisembodiment, a replacement heart valve 162 may include a flexiblematerial 164, optionally part of the fabric covering 166 of valve 162,which secures the three commisures 168, 170, 172 together at theirrespective distal ends 168 a, 170 a, 172 a. It will be appreciated thatflexible material 164 may be stitched to the interior aortic wall inconjunction with commisures 168, 170, 172. Thus, material 164 willprevent distal ends 168 a, 170 a, 172 a from expanding away from oneanother as occurs during late sinotubular enlargement of the aorta.Therefore, this prevents valve failure as a result.

[0047] As further shown in FIGS. 9, 9A and 9B, an alternative embodimentof a positioning and stabilizing device 180 includes an annular portion182 constructed from separate sections 182 a, 182 b, 182 c, and aplurality of three stabilizers 184, 186, 188. Stabilizer 184, 186, 188again are shown as three-legged structures for purposes previouslydescribed. In this embodiment, however, stabilizers 184, 186, 188 areretained within loops 190, which may be suture loops sewn into fabric166. It will be appreciated that other types of retaining structure maybe used to at least temporarily retain stabilizers 184, 186, 188. Inthis embodiment, connectable end portions 192, 194, formed respectivelyas male and female portions, may be used to make various connections anddisconnections on device 180. For example, lower ends of adjacentstabilizers 184, 186, 188 may be connected at a junction 196 as shown inFIG. 9. This may provide more consistent support along the edges ofcommisures 168, 170, 172. As further shown in FIG. 9B, stabilizers 184,186, 188 may be completely disconnectable from annular portion 182 whilealso allowing selective disconnection of sections 182 a, 182 b, 182 c.This may be accomplished through the use of connecting elements 198having respective female connecting portions 198 a for engaging maleconnecting portions 192. It will be understood that many alternativeconnectors and structures may be substituted for those shown whileretaining the basic function and general concepts expressed herein.

[0048]FIG. 10 illustrates a heart valve replacement apparatus 200comprised a replacement heart valve 202, which may be formed frombiological tissue or synthetic biologically compatible material. Heartvalve 202 is again illustrated with three commisures 204, 206, 208, asis typical for replacement aortic valves. A positioning and stabilizingdevice 210 is fastened to the outside of valve 202, for example, bysuture loops 211. This embodiment of the invention does not have anyconnection between the distal ends 204 a, 206 a, 208 a of commisures204, 206, 208 or at the distal end of positioning and stabilizing device210. Also, in this embodiment positioning and stabilizing device 210 isformed in three sections 212, 214, 216 removably connected together atjunctions 218, 220, 222. These connections may be similar to those shownin FIG. 9B. Other types of connections may be used as well. Use of thisembodiment of the invention will be similar to the previous embodiments,except that sections 212, 214, 216 may be removed individually fromheart valve 202 following completion of its securement within the aorta.Sections 212, 214, 216 are preferably formed of a highly flexibleplastic or metal which is biocompatible. This embodiment providescertain advantages, such as allowing one or more of the sections 212,214, 216 to remain in place following surgery and providing additionalroom for a surgeon to access commisures 204, 206, 208 while suturing orotherwise securing commisures 204, 206, 208 to the aortic wall. It willbe appreciated that other configurations and numbers of legs andsections may be utilized by those of ordinary skill.

[0049]FIG. 11 illustrates an expansion device 240 useful for expanding avessel, such as the aorta, during valve replacement procedures. In thisembodiment, expansion device may be formed as a collapsible andexpandable structure, such as by being formed of shape memory materialas described with respect to FIGS. 8A and 8B. It will be appreciatedthat FIG. 11 shows the expanded condition only. Expansion device 240 mayhave three extensions 242, 244, 246 of a desired length for dispositionbetween the respective commisures of an aortic replacement valve. Device240 need not be attached to heart valve commisures, but may be used toexpand the collapsed aorta to the proper flared shape thereby assistingthe surgeon during a heart valve replacement procedure. This deviceovercomes the drawbacks of typical retractors which tend to distort theshape of the collapsed aorta and mislead the surgeon as to the correctposition and orientation of the heart valve. Device 240 may be formed invarious manners to be collapsible and selectively expandable, such asthrough the use of mechanically expandable portions or, preferably,expandable shape memory portions.

[0050]FIGS. 12, 13A and 13B illustrate an alternative collapsible andexpandable retraction device 250. This device may be formed from a meshor screen material and includes edge portions 252, 254 which allowexpanding and contracting of the device. An upper end 256 is formed witha greater diameter than a lower end 258 in the expanded, operativeposition shown in FIGS. 12 and 13B. This allows a surgeon to havegreater access into and through the device to manipulate and, forexample, suture a replacement heart valve in place below device 250within the aorta. In use, and referring back to FIG. 1, a surgeon willinsert the device 250 in the collapsed form shown in FIG. 13A throughopening 12 such that lower end 258 is situated within aorta 10 and upperend 256 is exposed. The surgeon will then allow device 250 to expandthrough its own resilience or through a shape memory property to theposition shown in FIG. 13B. Alternatively, other activation structure ormeans may be provided for attaining the expanded condition. Onceexpanded, aorta 10 generally assumes a natural, pressurized shapeallowing placement and implantation of replacement valve 20 in a moreefficient and accurate manner. It will be understood that the expansiondevices shown in FIGS. 11 through 13B are illustrated in the simplestcurrently contemplated forms. It is further contemplated that additionalhandles or other support and actuation structure may be added whileachieving the same general advantages of these embodiments.

[0051] While the present invention has been illustrated by a descriptionof a preferred embodiment and while this embodiment has been describedin some detail, it is not the intention of the Applicants to restrict orin any way limit the scope of the appended claims to such detail.Additional advantages and modifications will readily appear to thoseskilled in the art. The various features and concepts of the inventionmay be used alone or in numerous combinations depending on the needs andpreferences of the user. This has been a description of the presentinvention, along with the preferred methods of practicing the presentinvention as currently known.

However, the invention itself should only be defined by the appendedclaims, wherein we claim:
 1. A replacement heart valve for implantationwithin a vessel, the replacement heart valve comprising: an annularbase, a plurality of commisures extending from the annular base atspaced apart positions, said commisures having proximal ends connectedwith said annular base and opposite distal ends, and a flexible fabricmaterial connecting the distal ends of said commisures and adapted to besecured to said vessel during implantation.
 2. An expandable andcollapsible vessel retraction device comprising: a body movable betweenexpanded and collapsed conditions such that, in the collapsed conditionthe body may be inserted into an open vessel and actuated into theexpanded condition whereby said vessel expands into a shapesubstantially corresponding to the natural pressurized shape of thevessel.
 3. The vessel retraction device of claim 2, wherein the body isgenerally tubular.
 4. The vessel retraction device of claim 2, whereinthe body is at least partially formed of a shape memory material.
 5. Amethod of implanting a replacement heart valve including an annular baseand a plurality of commisures extending from spaced apart positions ofthe annular base, the method comprising: inserting said replacementheart valve into a patient, connecting at least one commisure stabilizerto each of said commisures of said replacement heart valve either beforeor after inserting said replacement heart valve, securing saidreplacement heart valve within the patient using said commisurestabilizers to orient the commisures of the replacement heart valve, andremoving said commisure stabilizers from the patient leaving the securedreplacement heart valve in place.
 6. A method of implanting areplacement heart valve including an annular base and a plurality ofcommisures extending from spaced apart positions of the annular base,the method comprising: connecting three commisure stabilizers of apositioning and stabilizing device to the respective three commisures ofsaid replacement heart valve, inserting said replacement heart valveinto a patient, securing said replacement heart valve within the patientusing said commisure stabilizers to orient the three commisures of saidreplacement heart valve, and removing said positioning and stabilizingdevice from the patient leaving the secured replacement heart valve inplace.